The present invention relates to an apparatus and method, particularly but not exclusively, for assisting in deploying and/or securing a tubular section referred to as a “tubular member” within a liner or borehole.
Oil or gas wells are conventionally drilled with a drill string at which point the open hole is not lined, hereinafter referred to as a “borehole”. After drilling, the oil, water or gas well is typically completed thereafter with a casing or liner and a production tubing, all of which from here on are referred to as a “tubular”.
Conventionally, during the drilling, production or workover phase of an oil, water or gas well, there may be a requirement to provide a patch or temporary casing across an interval, such as a damaged section of liner, or an open hole section of the borehole. Additionally, there may be a requirement to cut a tubular (such as a section of casing) downhole, remove the upper free part and replace it with a new upper length of tubular in an operation know as “tie back” or ‘casing reconnect’ and in such a situation it is important to obtain a solid metal to metal seal between the lower “old” tubular section and upper “new” tubular section. Further, there may be a requirement to create an isolation barrier between two zones in an annular space in a well.
The present applicants have developed a technology where a tubular metal portion is forced radially outwardly by the use of fluid pressure acting directly on the portion. Sufficient hydraulic fluid pressure is applied to move the tubular metal portion radially outwards and cause the tubular metal portion to morph itself onto a generally cylindrical structure in which it is located. The portion undergoes plastic deformation and, if morphed to a generally cylindrical metal structure, the metal structure will undergo elastic deformation to expand by a small percentage as contact is made. When the pressure is released the metal structure returns to its original dimensions and will create a seal against the plastically deformed tubular metal portion. During the morphing (hydroforming) process, both the inner and outer surfaces of the tubular metal portion will take up the shape of the surface of the wall of the cylindrical structure. This morphed tubular is therefore ideally suited for creating a seal between a liner and previously set casing or liner which is worn and presents an irregular internal surface. The morphed tubular metal portion may also be a sleeve if mounted around a supporting tubular body, being sealed at each end of the sleeve to create a chamber between the inner surface of the sleeve and the outer surface of the body. A port is arranged through the body so that fluid can be pumped into the chamber from the throughbore of the body. This morphed isolation barrier is ideally suited for creating a seal between a tubular string and an open borehole.
WO2007/119052 and WO2012/127229, both to the present Applicants, show assemblies based on morphing one tubular within another. A morphed isolation barrier is disclosed in U.S. Pat. No. 7,306,033, which is incorporated herein by reference.
In order to morph the tubular metal section in a wellbore, fluid at a high pressure must be delivered to the location. It will be appreciated that the location may be thousands of feet in depth and thus pumping fluid from the surface will have drawbacks in that, the fluid pressure will reduce with depth and cannot be adequately calculated to ensure sufficient morphing pressure is reached. Additionally, it may not be desirable to pump such high fluid pressure through the tubing string for many well designs.
To overcome this, the present applicants have proposed a hydraulic fluid delivery tool or morph tool which can be run into the string from surface by means of coiled tubing or other suitable method. The tool is provided with upper and lower seals, which are operable to radially expand and seal against the inner surface of the string at a pair of spaced apart locations in order to isolate an internal portion of the string between the seals at the desired location. Fluid at high pressure can then be delivered to the location via a port in fluid communication with the interior of the string. For deep water projects a pressure intensifier is typically coupled to the hydraulic fluid delivery tool to increase the fluid pressure for morphing.
The upper and lower seals operate like the elastomeric or rubber seals found on packers. The use of radially expandable packers is well known in the art. Generally, there are two types of packers, the first type is inflatable rubber packers and the second type is compact rubber packers. These packers typically operate by requiring a control line to surface by which hydraulic fluid is either injected into the inflatable rubber packer to cause its expansion; or used against a wedge element so that the annular compact rubber seal expands by being forced up the wedge. A disadvantage of these arrangements is in maintaining sufficient pressure to keep the seal and prevent leakage.
In order to create radial expansion of the seals, the present Applicants have developed a sealing device described in GB 2425803. The sealing device comprises:—at least one substantially cylindrical inner element; at least one seal assembly; and a displacement means operable to apply a force on the said seal assembly; where the said inner element comprises a wedge member, and the said seal assembly is slidable over the wedge member along the longitudinal direction of the inner element, wherein the said seal assembly expands radially outward when forced over the wedge member; the seal assembly comprising a radially expandable annular seal supported by at least one radially expandable support sleeve; characterised in that the support sleeve forms a substantially continuous support surface towards the said annular seal in both expanded and non-expanded positions.
This is a complex construction with interleaved fingers to achieve the continuous support sleeve. When provided as a morph tool a further disadvantage of this construction is in the possibility that the fingers and wedges fail to release when the morph is complete and the tool needs to be removed.
It is an object of the present invention to provide a hydraulic fluid delivery tool for morphing tubulars downhole which obviates or mitigates at least some of the disadvantages of the prior art.